thompson



2 Sheets-Sheet '1.

(No Model.)

I 0. W. THOMPSON.

OUT-OFF VALVE MECHANISM.

Patented Apr. 7, 1896.

ANDREW EGRMMM.PHUTOMTMQWASHINGTONDC.

2 SheetsSheet 2.

(No Model.)

0 W THOMPSON v GUT-OFF VALVE MECHANISM.

No. 557,916. Patented Apr. 7,1896.

fnveniar;

W 'inesses aid f /f UNITED STATES COURTENAY W. THOMPSON, OF LONDON,

C-UT-OFF-VALVE M EC HANISM.

PATENT OFFICE.

ENGLAND.

SPECIFICATION forming part of Letters Patent No. 557,926, dated April'7, 1896. Application filed July 20, 1895. Serial No. 556,555. (Nomodel.)

To all whom it may concern.-

- Be it known that I, OOURTENAY WILLIAM THOMPSON, engineer, a subject ofthe Queen of Great Britain and Ireland, residing at 5 Fair Street,Tooley Street, London, in the county of Surrey, England, have inventedcertain Improvements in or Connected with Cut-Od- Valve Mechanism forEngines Worked by Steam or other Expansible Fluid, of which thefollowing is a specification.

My invention relates to the cut-off-valve mechanism of engines Worked bysteam or other expansible fluid, the said cutoff valves being used withslide-valves which may be flat, piston, oscillating, or of other kind;'and my said invention has for its object to produce simple andeffective mechanism for the purpose of regulating the cut-off either byhand or by the governor.

According to my invention I combine with the cut-off valve a mechanismsimilar in its movements to those of any ordinary or suitablesteam-engine reversing-gear, and I so adapt such gear and connect it tothe cut-off valve that I vary the expansion to any extent desired bymoving the said reversing-gear to either the forward or the reverseposition or to any intermediate position; but I so adapt such gear thatthe cut-ofi-valve mechanism is not effective to reverse the engine,which requires to be done independently. I may adapt any ordinary andsuitable reversinggear, as aforesaid, to the cutoff valves. Forinstance, I may use the double eccentric reversing link-gear or J oysgear or any of the numerous combinations of mechanism from which aresultant movement for the cut-oifvalve rod is obtained, the expansionbeing varied by moving the said gear to the forward, reverse, orintermediate position.

I describe the cut-off mechanism herein set forth by reference to and bycomparison with suitable reversing mechanisms, because it will bethereby readily understood (in all its modifications) by engineers; butI wish it to be understood that though the properties of the movementsare similar in both cases, yet, on the contrary, the application andfunctions of the two mechanisms are conspicuously different-namely, thefunctions of such cut-off mechanism are not effective to reverse theengine, but are adapted to effect wide variations in the rate 0expansionand that when hereinbefore I h e described the positions of thecut-off-valve mechanism as forward or reverse posit ons or otherpositions I thereby referred to e uivalent positions in an ordinaryreversin -gear. All steam-engine reversing-gears have a central orintermediate position, wit the forward and reverse positions on eitherside, and this cut-off mechan ism has sil ilar properties; buthereinafter I will design e the equivalents thus: the f0rward positio asthe late cutoff position and the reve 'se position as the early cutoffposition with the intermediate positions.

Great val ety in expansion is obtained by this cut-o f-valve mechanismand cut-01f valves, b cause in the late cut-off position of the cut-omechanism the major part of the closing m vement of the cut-off valvesis ob tained duri the later portion of the stroke of the main iston, andin the early cutoff position of the cut-off mechanism the major part ofthe closing movement of the cut-off valves is obtained during theearlier portion of the stroke of the main piston, and proportionatelyfor intermediate positions in the cut-off mechanism.

I may operate the cut-off slides on the back of main-valve slide-valvesof any preferred construction or on the back of a fixed plate, the portsof which plate communicate suitably with openings for the motive fluidin the principal valve, with which latter the fixed plate may, ifdesired, be connected to balance the pressure of the motive fluid onthem.

I will describe with reference to the accompanying drawings manners inwhich my invention may be carried into effect; but I do not limit myselfto the precise examples shown.

The accompanying drawings illustrate arrangements according to myinvention.

Figure 1 is a diagrammatic view illustrative of my invention. Figs. 2and 3 are sectional views of forms of slide and cut-off valves which maybe employed in carrying my invention into effect, and Figs. 4, 5, and 6are diagrams illustrative ofdifferent forms the face on which the mainvalve slides.

of mechanism whichmay be employed to 0p erate the cut-01f valves.

Fig. 1 illustrates a cut-off slide-valve such as is shown separately inFig. 2, combined with a gear of such a nature as is shown separately inFig. 6, and wherein the main valve may be operated in any convenientmanner which is not shown.

Fig. 2 shows separately a cut-off valve operating on the back of a mainvalve. A B is C is the main valve. D and D are the cut-off slides, whichare operated by any ordinary or suitable reversing valve-gear, ashereinbefore explained.

Fig. 3 illustrates a cutoff valve operating on the back of a fixedplate. A B is the face on which the main valve slides. O is the mainvalve. E is the fixed plate, shown as being connected to thepressure-relief piston E for relieving the pressure on the main valve 0.D is the cut-off valve, which is operated by any ordinary or suitablereversing valve-gear, as hereinbefore explained. The ports F F in thefixed plate E cooperate between the steam-ports in the main valve 0 andthe cut-off valve D.

In Fig. 3 the cut-off valve D is shown as one plate with a fixed lead,whereas in Fig. 2 the cut-off valve is shown in two piecesD and D,whereby they may act as starting-valves and their lead may be adjustedand the rate of expansion further varied by adjusting the valves D and Dto and from each other, which may be effected by any ordinary orsuitable means; but it will be understood that the cut-off valve may bearranged as either one or two plates in either of these cases.

The reversing expansion valvegear may be regulated by hand or by agovernor, and also the adjustment of the two cut-off plates may beregulated by hand or by a governor by any of the ordinary or suitableattachments for effecting the analogous movements of the sliding partsin reversin -gears.

The cut-off valves shown in Figs. 2 and 3 may operate in either the sameor the oppo site direction to that of the main valves.

Figs. 4, 5, and 6 illustrate a few varieties of cut-off-valve mechanismsuitable for combination with cut-off valves according to my invention.In all these figures O is the cylinder. P is the piston. A B is the faceon which the main valve slides. II represents the cross-head. E is thecrank-shaft. F is the crank-pin. M M is the variable expansion-link. Sis the attachment for the cut-offvalve rod. The arrow B shows thedirection in which the crank-shaft is turning. In all these cases theexpansion-link possesses the properties of movement of a reversing-link,but it is connected to the cut-off valve and therefore only regulatesthe rate of expansion.

The valve-slides are not shown in Figs. 4, 5, and 6 neither is the gearfor operating the main valve shown; but the main valve may be operatedin any convenient and ordinary manner.

Fig. 4 illustrates a mechanism (similar in its properties of movement toa double eccentric reversing-link) wherein n is the late cut-offeccentric, and 0 is the early cut-off eccentric. m is the late cut-offposition in the link, and m is the early cut-off position in the link,and such link m m may be raised or lowered by hand or by a governor.

Fig. 5 illustrates a mechanism suitable for the purpose of my invention,similar in its properties of movement to a reversing-gear combining twomovements from which a resultant movement is obtained for the valverod,being the reversing or variable expan sion eccentric and h the constantlead and lap eccentric. The eccentric 70 operates the rocking shaft 71,and the eccentric h operates the rocking shaft 11. The rocking shaft atransmits its movement to one end of the swing ing lever Q by means ofthe constant travelcrank. The rocking shaft 02 transmits its movement tothe other end of the swinging lever Q by means of the variableexpansion-link m m. Here an is the late cut-oif position and m is theearly cut-off position in the link m m. The block T may be raised orlowered in the link m m by hand or by a governor. m is a link on therocking shaft 91/ for the operation of the valves of other cylindersoperating at right angles to the cylinder shown.

Fig. 6 illustrates a mechanism also suitable for the purposes of myinvention, similar in its properties of movement to a reversinggearcombining two movements from which a resultant movement is obtained forthe valve-rod, in which at m correspond to the reversing-link. Therocking shaft n rocks the variable expansion-link m m, in which link onis the late cut-off position and m is the early cut-off position. Therocking shaft n is rocked by any convenient mechanism operating at rightangles to the crank-pin F and the lever Q gives the constant leadmovement. The lever Q receives its movement from the cross-head II bymeans of the rod II II and is fulcrumed at w. The block T carrying thefulcrum 10 may be raised or lowered in the variable expansion-link m mby hand or by a governor.

In Fig. 4 the two eccentrics n and 0 have equal and symmetrical anglesof advance or lead, when the lead of the cut-off valve will always bethe same; but the angles of lead of the two eccentrics may be variedrelatively to each other, thereby varying the lead in the slides; butstill the feature of my invention may be retained, and similarly thelead may be varied in other gears hereinbefore referrcd to.

WVhat I claim is- The combination with the main valve and cut-off valveof an engine, of a cut-off-valve gear consisting of a block connected tothe cut-off valve and slidably mounted in alink,

such as is hereinbefore defined, and operated name to this specificationin the presence of independently of the main-Valve block, the twosubscribing witnesses. said cut-off-valve block being connected with amoving part of the engine so that the two 0. \V. THOMPSON. 5 motionsthus secured effect different degrees WVitnesses:

of cut-off, substantially as described. J NO. LLOYD,

In'testimony whereof I have signed my HENRY R. JONES.

